Chain Drop Problem

I am new to single speeding so I need some help on this. First 2 rides were awesome. My ride today dropped the chain twice. The first time I was realling mashing the cranks on a steep technical climb and about went over the handlebars when the chain dropped off. The second time I was basically spinning up a slight incline. About mile 3 and 5 on a short 9 mile ride.

My bike is a 2010 Stumpjumper single speed. Stock 32-20. It has the eccentric bottom bracket.

I have a 2010 Specialized Rockhopper SS and it too has an EBB.....it is a very similar bike to yours and I have never dropped the chain!! It sounds to me like your chain is waaaay too loose. Use that awesomely designed clamshell EBB that specialized gave your rockhopper and tighten up that chain before you really hurt yourself due to the chain drop issue!!

Could be a bad chainline or a bent tooth on ring or cog, too. But based on how infrequently this is happening, my first suspicion would be chain tension too loose. But don't over tighten... if it's tight, it's too tight.

Yeah, just tighten the EBB. If it's stock, I'm sure the chainline is correct and the chain is the appropriate length. If you're new to SS'ing, I'd just take it to the shop where you purchased the bike and harass the mechanic to help you tighten the EBB to the appropriate torque. Then you'll be out hammering without a worry in no time.

Dont be afraid to mess with your bike you will learn by doing. Test tightness of the chain by throwing your pedals backwards (I mean this literally stand your bike up and throw the pedal in the opposite direction that you pedal) it should spin at least a full 360 maybe a bit more. Go with that tightness and remember to keep your chain lubed and check your ebb's tightness on the regular because things wont stay the way you like it....it wouldnt be any fun if you never had to tinker anyways!!